share-social

Original：🇺🇸 English
Translated

This skill should be used when the user asks to "optimize for Instagram", "YouTube Shorts format", "make it 9:16", "square video", "TikTok format", "Reels format", "prepare for social media", "encode for Twitter", "optimize for Facebook", "LinkedIn video", "crop for portrait", or mentions any platform-specific video format or upload requirements.

11installs
Sourcegupsammy/claudest
Added on

NPX Install

npx skill4agent add gupsammy/claudest share-social

Tags

Translated version includes tags in frontmatter
video-optimizationsocial-media-videoffmpegffprobevideo-transcoding

SKILL.md Content

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Video Social

Prepare video for social media platforms: correct aspect ratios, resolutions, bitrates, and container settings.

Platform Presets

PlatformAspectMax ResolutionMax DurationVideo BitrateAudio
Instagram Feed4:5 portrait or 1:11080×1350 / 1080×108060s3.5 MbpsAAC 128k
Instagram Reels9:161080×192090s8 MbpsAAC 192k
TikTok9:161080×192010min8 MbpsAAC 192k
YouTube Shorts9:161080×192060s8 MbpsAAC 192k
YouTube Standard16:91920×1080unlimited8 Mbps (1080p)AAC 192k
Twitter / X16:9 or 1:11920×1200140s25 Mbps capAAC 128k
Facebook16:9 or 9:161920×1080240min4 MbpsAAC 128k
LinkedIn16:91920×108010min5 MbpsAAC 128k

Process

1. Identify platform

If the request is ambiguous (e.g., "make it vertical"), ask which platform — bitrate and audio requirements differ.

2. Probe source

bash
ffprobe -v quiet -print_format json -show_streams -show_format "$INPUT"
Extract: width, height, duration, existing bitrate, audio codec.

3. Determine required transforms

Compare probe output against the platform row in the presets table. Apply only the transforms that are actually needed:
  • Aspect ratio mismatch → crop or pad (see Key Decisions for the choice rule)
  • Resolution too large → scale down (never upscale; social platforms reject oversized files at upload)
  • Duration exceeds platform limit → trim; confirm cut point with user first
  • Bitrate over limit → re-encode with target bitrate (platforms reject or silently degrade over-bitrate uploads)
Exit condition: when all four properties (aspect ratio, resolution, duration, bitrate) are within platform bounds and 
-movflags +faststart
will be set, proceed to Step 4. If source already matches all properties, skip to Step 5 with a simple re-encode plan.

4. Construct command

Crop to fit (preferred when subject is centered):
bash
# 16:9 source → 9:16 (1080×1920), center crop:
ffmpeg -i "$INPUT" \
  -vf "crop=ih*9/16:ih,scale=1080:1920" \
  -c:v libx264 -b:v 8000k \
  -c:a aac -b:a 192k \
  -movflags +faststart "$OUTPUT"
Pad to fit (preserves full frame, adds letterbox/pillarbox):
bash
# 16:9 source → 9:16 with black bars:
ffmpeg -i "$INPUT" \
  -vf "scale=1080:-2,pad=1080:1920:(ow-iw)/2:(oh-ih)/2:black" \
  -c:v libx264 -b:v 8000k \
  -c:a aac -b:a 192k \
  -movflags +faststart "$OUTPUT"
Square (1:1) from 16:9 — center crop:
bash
ffmpeg -i "$INPUT" \
  -vf "crop=ih:ih,scale=1080:1080" \
  -c:v libx264 -b:v 3500k \
  -c:a aac -b:a 128k \
  -movflags +faststart "$OUTPUT"

5. Confirm

State: crop vs. pad choice, any trim, output resolution and bitrate, output path. Wait for approval.

6. Run and verify

After encoding, verify bitrate: 
ffprobe -v quiet -show_format "$OUTPUT" | grep bit_rate

Key Decisions

  • Always include 
    -movflags +faststart
    — relocates the moov atom to the file start, enabling progressive playback before full download. Required for all social platforms.
  • Crop vs. pad: default to crop for talking-head or centered subjects; default to pad for wide scenic shots or text-heavy content. When the user says "don't cut anything off", use pad. When uncertain with off-center subjects, ask before running.
  • Never upscale: if source is smaller than target resolution, scale to fit within bounds or keep original dimensions.